Sound-transmitter



(No Model.)

H. B. PORTER.

SOUND TRANSMITTPR; N0. Z46,55Z. Patented Aug. 30,1881.

ATTORNEYS;

rrno STATES PATENT OFFICE.

HENRY B.- PORTER, OF CHICAGO, ILLINOIS.

SOUND-TRANSMITTERf SPECIFICATION forming part of Letters Patent No. 246,552, dated August 30, 1881.

Application filed May 23, 1881. (No model.)

To all whom it may concern: 1

Be it known that I, HENRY B. PORTER, 0 Chicago, in the county of Cook and State of Illinois, have invented a new and Improved Sound-Transmitter; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being bad to the accompanying drawings, forming part of this specification, in which- Figure l is an inside view of the instrument with the front plate and diaphragm removed. Fig. 2 is a central cross-section of the same through the line a0 00. Fig. 3 is an outside view of the speaking-tube and face-plate. Fig. 4 is a view of the diaphragm.

My invention relates to that class of telephone-transmitters in which the undulations of the electric current in the wire are controlled by the varying pressure of a conducting-surface on a piece of carbon, which variations of pressure are controlled by the vibrations of a diaphragm, and which current is made through the contact-faces.

The invention consists in the peculiar construction hereinafter described.

In the drawings, A represents the cup or main chamber of the telephone, and B is the face-plate, having a conical orifice in the same, forming a mouth -piece. Between this chamber A and the plate B is secured by its edge the diaphragm C. Behind the diaphragm are three or more radially-arranged springs, D, converging toward the center, and carrying at their inner ends cups with blocks of carbon at. Resting between these blocks of carbon and the diaphragm are three platinum points, I) b I), carried in the ends of a three-pronged metal plate, 6. This plate is perforated and slides longitudinally over a central pin, 0, that is attached to the center part of the back of the main chamber, and is provided with a spiral spring, 01, whose tension serves to hold the plate 0, with its contacts 1), against the diaphragm. To keep the three points 0 always in registration with the carbons and prevent rotary action of plate 6, several guide-pins,f, are arranged parallel with the center pin, 0, and connected to the same back plate, 9, that carries pin 0. These pinsfpass through holes in plate 0, so that while the latter is free to vibrate over the pins in unison with the diaphragm it cannot turn. The springs D serve to hold the carbons against the points I); but the movement of these springs and their pressure on the diaphragm is limited by the cushioned stops h.

The electric circuit is made in the transmitter as follows: One wire, E, is attached to the plate g and is in electrical contact through pin 0 and plate 6 with all of the contacts I) I) b. The other one of the wires, K, is connected with all of the springs D and is in electrical contact with all of the carbons. Now, as the plate 6 vibrates in unison with the diaphragm, its contacts b are pressed against the carbon with greater or less force, and, by thus governing the conduction of the current through the same, regulates the electrical'impulses in the line-wire.

Having thus described my invention, what I claim as new is- 1. The combination, with the carbons mounted upon the springs D, of the diaphragm, the plate 0, having contacts I) interposed between the diaphragm and the carbons, and the pin c,passing loosely through the plate 0 to sustain it, and provided with a spiral spring for holding said plate against the diaphragm, as described.

2. The transmitter composed of case A and B, diaphragm C, radial arms D D D,carrying the carbons, cushioned stops it, the plate 6, with contacts I) resting between the carbons and the diaphragm, the supporting-pin c, with spring d, and the guide-pins f, all combined substantially as shown and described.

HENRY B. PORTER. 

